In his U.S. Pat. No. 4,082,296, issued on Apr. 4, 1978, P. Charles Stein provided a plurality of embodiments of sealing members for sealing between a rotating member and a housing. The sealing members were provided in certain embodiments in the form of a segmented seal ring resiliently mounted about a shaft to move toward and away from the shaft to provide a seal therebetween. In the circumferential sealing face of each segment which faces adjacent the shaft, predetermined precise grooves are provided which produce a negative hydrodynamic lift force and urge the seal ring segments toward the rotating shaft in order to reduce leakage thereacross.
In other embodiments of the Stein Patent, particularly the embodiment of FIGS. 8 and 9 thereof, the rotating member or shaft is provided with a circumferential flange therein and a unitary seal ring effects a seal between a radially disposed face on the flange and a radially disposed face on the seal ring which coacts with the adjacent radial face on the flange. In that arrangement, the seal ring, which may be formed of circumferential segments, but normally from a single unitary ring, has on the sealing face thereof the grooves which produce the aforedescribed negative hydrodynamic lifting force between the seal ring and the rotatable flange to provide the reduced seal leakage.
In certain applications of the Stein Patent seal rings, a seal is provided for use with a bidirectionally rotatable shaft. In those examples, during forward rotation of the shaft, the medium in which the seal is operating (e.g., oil, water or gas), when the shaft is operating in its forward or normal direction, is swept out of the sealed grooves by a pumping action to provide the negative hydrodynamic lift force and to move the seal ring toward the rotatable member to effectuate greater sealing. In these applications, however, where a bidirectionally rotatable shaft is required to be sealed, when the seal operates in the reverse direction, the medium, especially a more viscous medium such as oil, pressure builds up in the grooves particularly adjacent the low pressure side of the seal ring which in certain instances is sufficient in magnitude to lift the seal ring away from the rotatable member causing it to leak. The purpose of this invention is to provide a modification of the Stein Patent seal arrangements for use with bidirectionally rotatable members to overcome a potential leakage problem with the seal ring when the rotatable member is operated in reverse. Any potential problem which occurs during reverse rotation of the shaft is solved by this invention.